agent provocateur

 
Pronunciation: /ˌaʒɒ̃ prəˌvɒkəˈtəː, aʒɑ̃ pʀɔvɔkatøʀ/

noun (plural agents provocateurs pronunc. )

  • a person employed to induce others to break the law so that they can be convicted.

Origin:

late 19th century: French, literally 'provocative agent'